Laszlo Bock, who runs human resources for Google, told the Journal the algorithm helps the company "get inside people's heads even before they know they might leave."

The newspaper said Google officials were reluctant to share details of the formula, which is still being tested, but it had already identified employees "who felt underused, a key complaint among those who contemplate leaving."

Edward Lawler, director of the Centre for Effective Organisations at the University of Southern California, told the Journal Google was "clearly ahead of the curve" in taking a more quantitative approach to personnel decisions.